Fragment Propagation and Colonization Ability Enhanced and Varied at Node Level after Escaping from Apical Dominance in Submerged Macrophytes

Aquatic plants develop strong fragment propagation and colonization ability to endure the natural disturbances. However, detailed research of ability to endure the natural disturbances has been lacking to date. Therefore, reproduction （shoot） and colonization （root） of shoot fragments of Potamogeton crispus L. with or without apices were investigated for the effect of apical dominance, and the growth of decapitated shoot fragments at three lengths （2, 4, 6 cm） was compared. Meanwhile, fragment propagation at levels of bud position was studied for bud position effect after escaping from apical dominance. The results showed significant increases occurred in the outgrowth of lateral branches on fragments decapitated compared with the fragments with apices, implying that apical dominance exists. Different lengths of fragments showed little difference in biomass allocations, but significant differences were noted in their propagation. Meanwhile, the effect of bud position was verified, due to the significant difference of average reproduction per node among the three length groups. Thus, the present study has made progress in the current understanding of aquatic plant dispersion among natural systems and contributes to improve methods of in vitro propagation for re-implantation purposes.

Dispersal of invasive Phytolacca americana seeds by birds in an urban garden in China

Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations,few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context.We evaluated the role of bird vectors in the dispersal of pokeweed(Phytolacca americana),a North American herb that is invasive in urban gardens in China.Fruiting P.americana attracted both generalist and specialist bird species that fed on and dispersed its seeds.The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers.Seedling numbers of P.americana were strongly associated with the perching behavior of frugivorous birds.If newly recruited bird species use seedling-safe perching sites,the P.americana will regenerate faster,which would enhance its invasive potential.Based on our observations,we conclude that the 2 main bird vectors,P.sinensis and U.erythrorhyncha,provide potential effective dispersal agents for P.americana.Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens.

Response of wintering waterbird diversity to reclamation history and post-reclamation habitat along Yellow Sea coast

Waterbird diversity is one of the most important indicators for monitoring wetland quality.However,the increasing intensity of reclamation activities in recent decades caused the change of habitat landscape along coasts,which could affect the diversity of wintering waterbirds.Our study tried to investigate how reclamation history and postreclamation habitats influence the species richness,species abundance,and Shannon–Wiener diversity of wintering waterbirds along Yancheng coastal wetlands.A total of 68 waterbird species were recorded and the abundance pattern of wintering birds changed from 2009 to 2013.Species richness and abundance of wintering waterbirds varied in the different reclamation histories.Most importantly,the general linear mixed model highlighted the importance of reclamation history,post-reclamation habitat type,and their interactions for shaping both species abundance and Shannon–Wiener diversity of wintering waterbirds,but these variables did not affect the species richness of waterbirds.Furthermore,the random forest results also showed a positive association between reclamation history with species richness,species abundance,and Shannon–Wiener diversity of wintering waterbirds.Moreover,three post-reclamation habitat types,Suaeda glauca,bare flat,and fish pond,played important roles for wintering birds.Our results highlighted that reclamation history,post-reclamation habitats,and their interactions determined waterbird diversity.Given the growing threats to wetland ecosystems from reclamation activities,further research should find a balance between coastal reclamation and waterbird biodiversity conservation.